The Chushul Chakzam, or simply Chakzam which literally means "iron bridge" in Standard Tibetan, was a suspension bridge that spanned the Yarlung Tsangpo river in modern-day Qüxü County near Lhasa, Tibet. It was built in 1430 by Thang Tong Gyalpo. The southern bridgehead was built on the mountain Chowuri, which is sacred in Tibetan Buddhism. This mountain was a site where Guru Rinpoche and Trisong Detsen had meditated during the 8th Century. When it was built, its main section was the longest unsupported span in the world, with a central span estimated at around 150 yards.